The Role of Selected Wavelengths of Light in the Activity of Photosystem II in Gloeobacter violaceus.

Monika Kula-Maximenko,Kamil Jan Zieliński,Ireneusz Ślesak

doi:10.3390/ijms22084021

Abstract

Gloeobacter violaceus is a cyanobacteria species with a lack of thylakoids, while photosynthetic antennas, i.e., phycobilisomes (PBSs), photosystem II (PSII), and I (PSI), are located in the cytoplasmic membrane. We verified the hypothesis that blue–red (BR) light supplemented with a far-red (FR), ultraviolet A (UVA), and green (G) light can affect the photosynthetic electron transport chain in PSII and explain the differences in the growth of the G. violaceus culture. The cyanobacteria were cultured under different light conditions. The largest increase in G. violaceus biomass was observed only under BR + FR and BR + G light. Moreover, the shape of the G. violaceus cells was modified by the spectrum with the addition of G light. Furthermore, it was found that both the spectral composition of light and age of the cyanobacterial culture affect the different content of phycobiliproteins in the photosynthetic antennas (PBS). Most likely, in cells grown under light conditions with the addition of FR and G light, the average antenna size increased due to the inactivation of some reaction centers in PSII. Moreover, the role of PSI and gloeorhodopsin as supplementary sources of metabolic energy in the G. violaceus growth is discussed.

Highlights

Beata Myśliwa Kurdziel, Photosynthetic organisms have specific pigment–protein complexes called antennas that capture light energy and send excitation energy to the photosynthetic reaction centers, where the primary photochemical reactions occur
Conditions parison to other light conditions was related to the proliferation rate of the cyanobac The weaker intensity of the violet color of the cultures grown under BR light in comcells (Figure 1 and Supplementary Materials Figure S1)
Parison to other light conditions was related to the proliferation rate of the cyanobacterial cells (Figure 1 and Supplementary Materials Figure S1)

Summary

Introduction

Beata Myśliwa Kurdziel, Photosynthetic organisms have specific pigment–protein complexes called antennas that capture light energy and send excitation energy to the photosynthetic reaction centers, where the primary photochemical reactions occur. Cyanobacteria are believed to be primordial organisms that perform oxygenic photosynthesis and their antenna systems consist of phycobiliproteins, which form the phycobilisome (PBS) complex, located outside of thylakoid membranes [1,2,3,4,5,6]. Instead of LHC, they have PBSs, which contain three main types of phycobiliproteins:. The excited electrons, that are generated by light in the antennas, are transferred to the PS I and PS II reaction centers and initiate the photosynthetic electron transport chain (PETC).

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Discussion

Conclusion